Map information system

ABSTRACT

A map information system includes a database management device configured to manage a map database used for vehicle driving support control. The map database includes road marking map information that indicates a position of a specific road marking including at least one of a stop line and a pedestrian crossing. The database management device is further configured to: detect a road marking candidate being a candidate for the specific road marking around a vehicle; recognize vehicle behavior of at least one of the vehicle and another vehicle in a period when passing the road marking candidate; determine, based on the vehicle behavior, an evaluation value that indicates certainty of the road marking candidate being the specific road marking; and register the road marking candidate having the evaluation value equal to or higher than a threshold, as the specific road marking, in the road marking map information.

BACKGROUND Technical Field

The present disclosure relates to a technique that manages mapinformation used for driving support control that supports driving of avehicle.

Background Art

Patent Literature 1 discloses a vehicle control device installed on avehicle. The vehicle control device images a road surface ahead of thevehicle by using a camera. The vehicle control device analyzes the roadsurface image to detect a stop line on the road surface. Moreover, thevehicle control device calculates reliability of the detected stop linebeing actually present, based on brightness distribution of a pluralityof points included in the road surface image. When the reliability isequal to or higher than a predetermined value, the vehicle controldevice executes vehicle travel control required for stopping the vehiclebefore the detected stop line.

Patent Literature 2 discloses a traffic information providing system.The traffic information providing system includes an in-vehicle devicehaving a navigation function and a traffic information center thatprovides a vehicle with traffic information (traffic jam information).The in-vehicle device determines whether or not there is a deviationbetween actual travel information of the vehicle and the trafficinformation provided from the traffic information center. When there isthe deviation, the in-vehicle device sends deviation information to thetraffic information center. The traffic information center updates thetraffic information based on the deviation information.

LIST OF RELATED ART

Patent Literature 1: Japanese Unexamined Patent Application PublicationNo. 2011-063131

Patent Literature 2: Japanese Unexamined Patent Application PublicationNo. 2013-109625

SUMMARY

Let us consider driving support control that supports driving of avehicle. It is conceivable in the driving support control to use mapinformation that indicates a position of a specific road marking such asa stop line and a pedestrian crossing. In order to increase accuracy ofthe driving support control, it is necessary to increase accuracy of themap information. In order to obtain more accurate map information, it isdesirable to more accurately determine presence of the specific roadmarking.

According to the technique disclosed in the above-mentioned PatentLiterature 1, the reliability of the stop line being actually present iscalculated based on the brightness distribution of a plurality of pointsincluded in the road surface image. However, accuracy of the reliabilitycalculation based on the brightness distribution is insufficient. Forexample, a white line defining a lane is erroneously detected as a stopline, and furthermore its reliability is erroneously determined to behigh.

An object of the present disclosure is to provide a technique that canincrease accuracy of road marking map information that is used fordriving support control and indicates a position of a specific roadmarking.

In an aspect of the present disclosure, a map information system isprovided.

The map information system includes a database management device.

The database management device manages a map database used for drivingsupport control that supports driving of a vehicle.

The map database includes road marking map information that indicates aposition of a specific road marking including at least one of a stopline and a pedestrian crossing.

Driving environment information indicates driving environment for thevehicle that is acquired by a sensor installed on the vehicle.

The database management device is further configured to:

detect a road marking candidate being a candidate for the specific roadmarking around the vehicle, based on the driving environmentinformation;

recognize vehicle behavior of at least one of the vehicle and anothervehicle in a period when passing the road marking candidate, based onthe driving environment information;

determine, based on the vehicle behavior, an evaluation value thatindicates certainty of the road marking candidate being the specificroad marking; and

register the road marking candidate having the evaluation value equal toor higher than a threshold, as the specific road marking, in the roadmarking map information.

According to the present disclosure, the database management devicedetects the road marking candidate around the vehicle, and determinesthe evaluation value that indicates certainty of the detected roadmarking candidate being the specific road marking. More specifically,the database management device recognizes the vehicle behavior of atleast one of the vehicle and another vehicle in a period when passingthe road marking candidate, based on the driving environmentinformation. The vehicle behavior with respect to the specific roadmarking is totally different from the vehicle behavior with respect toother road markings (for example, a lane marking). Therefore, using thevehicle behavior makes it possible to determine the evaluation valueregarding the specific road marking with high accuracy. The evaluationvalue being determined with high accuracy causes increase in accuracy(quality) of the road marking map information that is automaticallygenerated based on the evaluation value. Since the accuracy of the roadmarking map information is increased, accuracy of the driving supportcontrol using the road marking map information also is increased.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a conceptual diagram for explaining an outline of anembodiment of the present disclosure;

FIG. 2 is a conceptual diagram for explaining an example of road markingmap information regarding a stop line in the embodiment of the presentdisclosure;

FIG. 3 is a conceptual diagram for explaining an example of road markingmap information regarding a pedestrian crossing in the embodiment of thepresent disclosure;

FIG. 4 is a conceptual diagram for explaining a method of determining anevaluation value by a database management device according to theembodiment of the present disclosure;

FIG. 5 is a block diagram showing a configuration example of a drivingsupport control device according to the embodiment of the presentdisclosure;

FIG. 6 is a block diagram showing an example of driving environmentinformation used in the embodiment of the present disclosure;

FIG. 7 is a block diagram showing a first configuration example of thedatabase management device according to the embodiment of the presentdisclosure;

FIG. 8 is a block diagram showing a second configuration example of thedatabase management device according to the embodiment of the presentdisclosure;

FIG. 9 is a block diagram showing a third configuration example of thedatabase management device according to the embodiment of the presentdisclosure;

FIG. 10 is a flow chart showing processing by the database managementdevice according to the embodiment of the present disclosure;

FIG. 11 is a conceptual diagram for explaining a first example of amethod of determining the evaluation value based on vehicle behavior inthe embodiment of the present disclosure;

FIG. 12 is a conceptual diagram for explaining the first example of themethod of determining the evaluation value based on vehicle behavior inthe embodiment of the present disclosure;

FIG. 13 is a conceptual diagram for explaining a third example of themethod of determining the evaluation value based on vehicle behavior inthe embodiment of the present disclosure;

FIG. 14 is a conceptual diagram for explaining the third example of themethod of determining the evaluation value based on vehicle behavior inthe embodiment of the present disclosure;

FIG. 15 is a conceptual diagram for explaining a fourth example of themethod of determining the evaluation value based on vehicle behavior inthe embodiment of the present disclosure;

FIG. 16 is a conceptual diagram for explaining a fifth example of themethod of determining the evaluation value based on vehicle behavior inthe embodiment of the present disclosure;

FIG. 17 is a conceptual diagram for explaining the fifth example of themethod of determining the evaluation value based on vehicle behavior inthe embodiment of the present disclosure;

FIG. 18 is a conceptual diagram for explaining a sixth example of themethod of determining the evaluation value based on vehicle behavior inthe embodiment of the present disclosure;

FIG. 19 is a conceptual diagram for explaining the sixth example of themethod of determining the evaluation value based on vehicle behavior inthe embodiment of the present disclosure;

FIG. 20 is a conceptual diagram for explaining a seventh example of themethod of determining the evaluation value based on vehicle behavior inthe embodiment of the present disclosure;

FIG. 21 is a conceptual diagram for explaining the seventh example ofthe method of determining the evaluation value based on vehicle behaviorin the embodiment of the present disclosure;

FIG. 22 is a conceptual diagram for explaining an example of update of amandatory stop line evaluation value in the embodiment of the presentdisclosure;

FIG. 23 is a conceptual diagram for explaining another example of updateof the mandatory stop line evaluation value in the embodiment of thepresent disclosure;

FIG. 24 is a flow chart showing another example of processing by thedatabase management device according to the embodiment of the presentdisclosure; and

FIG. 25 is a flow chart showing still another example of processing bythe database management device according to the embodiment of thepresent disclosure.

EMBODIMENTS

Embodiments of the present disclosure will be described below withreference to the attached drawings.

1. Outline

1-1. Map Information System

FIG. 1 is a conceptual diagram for explaining an outline of the presentembodiment. A driving support control device 100 is installed on avehicle 1. The driving support control device 100 executes drivingsupport control that supports driving of the vehicle 1. Typically, thedriving support control includes at least one of steering control,acceleration control, and deceleration control. Such the driving supportcontrol is exemplified by automated driving control (autonomous drivingcontrol), trajectory-following control (path-following control), lanekeep assist control (lane tracing assist control), collision avoidancecontrol, and so forth.

In the driving support control, map information is often used. The mapinformation provides a variety of information associated with aposition. Here, the position is an absolute position and is defined inan absolute coordinate system (e.g. latitude, longitude, and altitude).A map database MAP_DB is a set of a variety of map information. Itshould be noted that the map database MAP_DB may be stored in a memorydevice of the vehicle 1, or may be stored in an external device outsidethe vehicle 1.

A map information system 10 according to the present embodiment is asystem that manages and utilizes the map database MAP_DB. Morespecifically, the map information system 10 includes the map databaseMAP_DB, an information acquisition device 20, and a database managementdevice 30. The map information system 10 may further include the drivingsupport control device 100 that utilizes the map database MAP_DB.

The information acquisition device 20 is installed on the vehicle 1. Theinformation acquisition device 20 uses a sensor installed on the vehicle1 to acquire a variety of information. Information acquired by thesensor installed on the vehicle 1 indicates driving environment for thevehicle, and such the information is hereinafter referred to as “drivingenvironment information 200”. For example, the driving environmentinformation 200 includes vehicle position information indicating aposition of the vehicle 1, vehicle state information indicating a stateof the vehicle 1, surrounding situation information indicating asituation around the vehicle 1, and so forth. The driving environmentinformation 200 is used for the driving support control by the drivingsupport control device 100 along with the map database MAP_DB.Furthermore, the driving environment information 200 is also used formanagement of the map database MAP_DB.

The database management device 30 manages the map database MAP_DB usedfor the driving support control. The management of the map databaseMAP_DB includes at least one of generation and update of the mapdatabase MAP_DB. It should be noted that the database management device30 may be installed on the vehicle 1, or may be included in an externaldevice outside the vehicle 1. Alternatively, the database managementdevice 30 may be distributed to the vehicle 1 and the external device.

1-2. Road Marking Map Information

In the present embodiment, we especially consider management of the mapinformation regarding a “road marking”. The road marking is a markingthat is drawn on a road surface. The road marking is exemplified by astop line, a pedestrian crossing (a crosswalk), a lane marking, and soforth. The lane marking, which is the road marking defining a lane,includes a lane boundary line and a center line.

The stop line is further classified into a mandatory stop line (amust-stop line) obligating to stop and another stop line. Every vehicleis required to always stop before the mandatory stop line. Typically, astop sign instructing to stop and/or a character road marking “STOP” isplaced in the vicinity of the mandatory stop line. On the other hand,the vehicle stops before a stop line other than the mandatory stop lineif necessary. For example, when a stop line is arranged before a trafficlight and the traffic light is a red light, the vehicle stops before thestop line. As another example, when a stop line is arranged before apedestrian crossing and a pedestrian is crossing the pedestriancrossing, the vehicle stops before the stop line.

The map database MAP_DB according to the present embodiment includesroad marking map information RM_MAP regarding a “specific road markingRM”. The specific road marking RM includes at least one of the stop lineand the pedestrian crossing. Meanwhile, the specific road marking RMdoes not include the lane marking.

The road marking map information RM_MAP indicates a position of thespecific road marking RM. The road marking map information RM_MAP mayindicate a position of the specific road marking RM and an “evaluationvalue” that are associated with each other. The evaluation valueindicates “certainty” that the specific road marking RM actually existsat the position indicated by the road marking map information RM_MAP.The certainty can be reworded as accuracy or reliability. The evaluationvalue can be reworded as a score.

FIG. 2 conceptually shows an example of the road marking map informationRM_MAP regarding the stop line. The road marking map information RM_MAPregarding the stop line indicates a position of the stop line.Typically, the stop line is a white line having a linear shape. In thatcase, the position of the stop line is expressed by positions [X1, Y1]and [X2, Y2] of both ends of the line.

In the example shown in FIG. 2, the road marking map information RM_MAPindicates a stop line evaluation value Psl and a mandatory stop lineevaluation value Pmsl in addition to the position. The position, thestop line evaluation value Psl, and the mandatory stop line evaluationvalue Pmsl are associated with each other. The stop line evaluationvalue Psl indicates certainty that the stop line actually exists at theposition indicated by the road marking map information RM_MAP. Themandatory stop line evaluation value Pmsl indicates certainty that themandatory stop line actually exists at the position indicated by theroad marking map information RM_MAP. When the stop line evaluation valuePsl is high and the mandatory stop line evaluation value Pmsl also ishigh, the mandatory stop line is likely to exist at the position. On theother hand, when the stop line evaluation value Psl is high and themandatory stop line evaluation value Pmsl is low, the stop line otherthan the mandatory stop line is likely to exist at the position.

FIG. 3 conceptually shows an example of the road marking map informationRM_MAP regarding the pedestrian crossing. The road marking mapinformation RM_MAP regarding the pedestrian crossing indicates aposition of the pedestrian crossing. Typically, the pedestrian crossinghas a stripe pattern that a plurality of white lines are arranged inparallel, and has a rectangle shape as a whole. In that case, theposition of the pedestrian crossing is expressed by positions [Xi, Yi](i=1 to 4) of four corners of the rectangle shape.

The road marking map information RM_MAP regarding the pedestriancrossing further indicates an arrangement direction A of the pedestriancrossing. The arrangement direction A is a direction orthogonal to theplurality of parallel lines constituting the pedestrian crossing.

In the example shown in FIG. 3, the road marking map information RM_MAPindicates a pedestrian crossing evaluation value Ppc in addition to theposition and the arrangement direction A. The position, the arrangementdirection A, and the pedestrian crossing evaluation value Ppc areassociated with each other. The pedestrian crossing evaluation value Ppcindicates certainty that the pedestrian crossing actually exists at theposition indicated by the road marking map information RM_MAP. When thepedestrian crossing evaluation value Ppc is high, the pedestriancrossing is likely to exist at the position indicated by the roadmarking map information RM_MAP.

1-3. Database Management Device

The database management device 30 according to the present embodimentmanages the road marking map information RM_MAP. The management of theroad marking map information RM_MAP includes at least one of generationand update of the road marking map information RM_MAP.

More specifically, the database management device 30 detects a candidatefor the specific road marking RM around the vehicle 1. The candidate forthe specific road marking RM around the vehicle 1 is hereinafterreferred to as a “road marking candidate”. The road marking candidateincludes at least one of a “stop line candidate” being a candidate forthe stop line and a “pedestrian crossing candidate” being a candidatefor the pedestrian crossing. The road marking candidate is detectablebased on the above-described driving environment information 200 (e.g.the surrounding situation information) acquired at the vehicle 1.

Subsequently, the database management device 30 determines an“evaluation value” regarding the detected road marking candidate. Theevaluation value indicates “certainty” of the detected road markingcandidate being the specific road marking RM. The certainty of thedetected road marking candidate being the specific road marking RM isequivalent to the certainty that the specific road marking RM actuallyexists at the detection position of the road marking candidate, that is,the evaluation value (Psl, Pmsl, Ppc) described in FIGS. 2 and 3. Forexample, the certainty of the detected stop line candidate being thestop line is equivalent to the certainty that the stop line actuallyexists at the detection position of the stop line candidate, that is,the stop line evaluation value Psl described above.

A method of determining the evaluation value by the database managementdevice 30 according to the present embodiment will be described withreference to FIG. 4. Not only the specific road marking RM such as thestop line and the pedestrian crossing but also the lane marking LM suchas a lane boundary line and a center line exists on the road surface.The road marking candidate detected based on the driving environmentinformation 200 may erroneously include the lane marking LM.

However, vehicle behavior of the vehicle 1 with respect to the specificroad marking RM is totally different from vehicle behavior of thevehicle 1 with respect to the lane marking LM. It is therefore possibleto determine (verify), based on the vehicle behavior of the vehicle 1,whether or not the road marking candidate is the specific road markingRM. In other words, it is possible to determine the evaluation valuebased on the vehicle behavior of the vehicle 1. The vehicle behavior ofthe vehicle 1 can be recognized based on the above-described drivingenvironment information 200 (e.g. the vehicle position information, thevehicle state information) acquired at the vehicle 1.

The same applies to vehicle behavior of another vehicle 2 around thevehicle 1. Vehicle behavior of said another vehicle 2 with respect tothe specific road marking RM is totally different from vehicle behaviorof said another vehicle 2 with respect to the lane marking LM. It istherefore possible to determine (verify), based on the vehicle behaviorof another vehicle 2, whether or not the road marking candidate is thespecific road marking RM. In other words, it is possible to determinethe evaluation value based on the vehicle behavior of another vehicle 2.The vehicle behavior of another vehicle 2 can be recognized based on theabove-described driving environment information 200 (e.g. thesurrounding situation information) acquired at the vehicle 1.

The database management device 30 recognizes the vehicle behavior of atleast one of the vehicle 1 and another vehicle 2 with respect to theroad marking candidate, based on the driving environment information200. More specifically, the database management device 30 recognizes thevehicle behavior of at least one of the vehicle 1 and another vehicle 2in a period when passing the road marking candidate, based on thedriving environment information 200. For example, the databasemanagement device 30 recognizes the vehicle behavior in a certainsection RNG including the position of the road marking candidate. Then,based on the recognized vehicle behavior, the database management device30 determines the evaluation value that indicates certainty of the roadmarking candidate being the specific road marking RM.

Furthermore, the database management device 30 registers the roadmarking candidate having the evaluation value equal to or higher than athreshold, as the specific road marking RM, in the road marking mapinformation RM_MAP. More specifically, the database management device 30registers the position of the specific road marking RM in the roadmarking map information RM_MAP. The database management device 30 mayregister the position of the specific road marking RM and the evaluationvalue associated with each other, in the road marking map informationRM_MAP (see FIGS. 2 and 3).

The database management device 30 may update the road marking mapinformation RM_MAP. For example, when the vehicle 1 repeatedly travels asame road, an identical road marking RM is repeatedly detected andinformation on the identical road marking RM is repeatedly acquired.Therefore, the database management device 30 can update informationregarding the specific road marking RM (i.e. a registered road marking)that is already registered in the road marking map information RM_MAP.For example, the database management device 30 updates the evaluationvalue regarding the registered road marking, based on the vehiclebehavior with respect to the road marking candidate corresponding to theregistered road marking.

The function of the database management device 30 can be achieved by thefollowing functional blocks. A road marking candidate detection unitdetects the road marking candidate around the vehicle 1, based on thedriving environment information 200. A vehicle behavior recognition unitrecognizes the vehicle behavior of at least one of the vehicle 1 andanother vehicle 2 in a period when passing the road marking candidate,based on the driving environment information 200. An evaluation valuedetermination unit determines, based on the vehicle behavior, theevaluation value that indicates certainty of the road marking candidatebeing the specific road marking RM. The map information update unitregisters the road marking candidate having the evaluation value equalto or higher than the threshold, as the specific road marking RM, in theroad marking map information RM_MAP. The map information update unit mayupdate the evaluation value regarding the registered road marking, basedon the vehicle behavior with respect to the road marking candidatecorresponding to the registered road marking. These functional blocksare realized by a processor executing a computer program stored in amemory device. The processor may be installed on the vehicle 1, or maybe included in an external device outside the vehicle 1. Alternatively,the processor may be distributed to the vehicle 1 and the externaldevice. In that case, the function of the database management device 30is divisionally handled by the vehicle 1 and the external device.

1-4. Effects

According to the present embodiment, as described above, the databasemanagement device 30 detects the road marking candidate around thevehicle 1, and determines the evaluation value that indicates certaintyof the detected road marking candidate being the specific road markingRM. More specifically, the database management device 30 recognizes thevehicle behavior of at least one of the vehicle 1 and another vehicle 2in a period when passing the road marking candidate, based on thedriving environment information 200. The vehicle behavior with respectto the specific road marking RM is totally different from the vehiclebehavior with respect to other road markings (e.g. the lane marking LM).Therefore, using the vehicle behavior makes it possible to determine theevaluation value regarding the specific road marking RM with highaccuracy.

As a comparative example, let us consider a case of determining whetheror not the road marking candidate is the specific road marking RM basedon brightness of road surface image. Not only the specific road markingRM such as the stop line and the pedestrian crossing but also the lanemarking LM such as a lane boundary line and a center line exists on theroad surface (see FIG. 4). The specific road marking RM and the lanemarking LM each has high brightness. Therefore, it is not possible todetermine with high accuracy whether or not the road marking candidateis the specific road marking RM based on the brightness of the roadsurface image. That is, it is not possible to determine the evaluationvalue with high accuracy.

According to the present embodiment, the road marking candidate havingthe evaluation value equal to or higher than the threshold is registeredas the specific road marking RM in the road marking map informationRM_MAP. The evaluation value being determined with high accuracy causesincrease in accuracy (quality) of the road marking map informationRM_MAP that is automatically generated based on the evaluation value.Moreover, when the road marking map information RM_MAP indicates theposition and the evaluation value, improvement in the evaluation valueleads directly to increase in accuracy (quality) of the road marking mapinformation RM_MAP. Since the accuracy of the road marking mapinformation RM_MAP is increased, accuracy of the driving support controlusing the road marking map information RM_MAP also is increased.

The database management device 30 may update the road marking mapinformation RM_MAP. Such the update processing causes further increasein the accuracy (quality) of the road marking map information RM_MAP. Asa result, the accuracy of the driving support control using the roadmarking map information RM_MAP also is further increased.

The map database MAP_DB and the database management device 30 may beinstalled on the vehicle 1. That is to say, all components of the mapinformation system 10 may be installed on the vehicle 1. In that case,the map information system 10 automatically executes, in the vehicle 1,all of the acquisition of the driving environment information 200, themanagement of the map database MAP_DB based on the driving environmentinformation 200, and the driving support control based on the mapdatabase MAP_DB. Such the map information system 10 can be referred toas a “self-learning driving support control system”. In particular, whenexecuting the automated driving control as the driving support control,such the map information system 10 can be referred to as a“self-learning automated driving system”.

It can be said that the map database MAP_DB is useful knowledge for thedriving support control. It can be said that the map information system10 according to the present embodiment automatically executes detection,verification, and accumulation of the knowledge.

Hereinafter, the map information system 10 according to the presentembodiment will be described in more detail.

2. Configuration Example of Map Information System 10

2-1. Configuration Example of Driving Support Control Device 100

FIG. 5 is a block diagram showing a configuration example of the drivingsupport control device 100 according to the present embodiment. Thedriving support control device 100 is installed on the vehicle 1 andincludes a surrounding situation sensor 110, a vehicle position sensor120, a vehicle state sensor 130, a communication device 140, an HMI(Human Machine Interface) unit 150, a travel device 160, and a controldevice (controller) 170.

The surrounding situation sensor 110 detects (recognizes) a situationaround the vehicle 1. The surrounding situation sensor 110 isexemplified by a camera (imaging device), a LIDAR (Laser ImagingDetection and Ranging), a radar, and so forth. The camera images asituation around the vehicle 1. The LIDAR uses laser beams to detect atarget around the vehicle 1. The radar uses radio waves to detect atarget around the vehicle 1.

The vehicle position sensor 120 detects a position and an orientation(e.g. azimuth) of the vehicle 1. For example, the vehicle positionsensor 120 includes a GPS (Global Positioning System) sensor. The GPSsensor receives signals transmitted from a plurality of GPS satellitesand calculates the position and the orientation of the vehicle 1 basedon the received signals.

The vehicle state sensor 130 detects a state of the vehicle 1. The stateof the vehicle 1 includes a speed of the vehicle 1 (i.e. a vehiclespeed), an acceleration, a steering angle, a yaw rate, and so forth. Thestate of the vehicle 1 further includes a driving operation by a driverof the vehicle 1. The driving operation includes an accelerationoperation, a braking operation, and a steering operation.

The communication device 140 communicates with the outside of thevehicle 1. For example, the communication device 140 communicates withan external device outside the vehicle 1 through a communicationnetwork. The communication device 140 may perform a V2I communication(vehicle-to-infrastructure communication) with a surroundinginfrastructure. The communication device 140 may perform a V2Vcommunication (vehicle-to-vehicle communication) with a surroundingvehicle.

The HMI unit 150 is an interface for proving the driver with informationand receiving information from the driver. More specifically, the HMIunit 150 includes an input device and an output device. The input deviceis exemplified by a touch panel, a switch, a microphone, and the like.The output device is exemplified by a display device, a speaker, and thelike.

The travel device 160 includes a steering device, a driving device, anda braking device. The steering device turns wheels. The driving deviceis a power source that generates a driving force. The driving device isexemplified by an engine and an electric motor. The braking devicegenerates a braking force.

The control device (controller) 170 is a microcomputer including aprocessor 171 and a memory device 172. The control device 170 is alsocalled an ECU (Electronic Control Unit). A variety of processing by thecontrol device 170 is achieved by the processor 171 executing a controlprogram stored in the memory device 172.

For example, the control device 170 acquires necessary map informationMAP from the map database MAP_DB. The map information MAP includes theroad marking map information RM_MAP described above. In addition, themap information MAP includes a road map and a navigation map commonlyused. In a case where the map database MAP_DB is installed on thevehicle 1, the control device 170 acquires necessary map information MAPfrom the map database MAP_DB. In another case where the map databaseMAP_DB exists outside the vehicle 1, the control device 170 acquiresnecessary map information MAP through the communication device 140. Themap information MAP is stored in the memory device 172 and read out fromthe memory device 172 to be used, as appropriate.

Moreover, the control device 170 acquires the driving environmentinformation 200. The driving environment information 200 is stored inthe memory device 172 and read out from the memory device 172 to beused, as appropriate.

FIG. 6 is a block diagram showing an example of the driving environmentinformation 200. The driving environment information 200 includessurrounding situation information 210, vehicle position information 220,vehicle state information 230, and delivery information 240.

The surrounding situation information 210 indicates the situation aroundthe vehicle 1. The surrounding situation information 210 is informationobtained from a result of detection by the surrounding situation sensor110. For example, the surrounding situation information 210 includesimage information obtained by the camera. The surrounding situationinformation 210 may include measurement information obtained by theLIDAR and the radar. The surrounding situation information 210 mayinclude target information regarding a target detected based on theimage information and the measurement information. The target around thevehicle 1 is exemplified by a surrounding vehicle, a pedestrian, a whiteline, a roadside structure, a sign, and so forth. The target informationincludes a relative position, a relative velocity, and the like of thedetected target. The control device 170 acquires the surroundingsituation information 210 based on the result of detection by thesurrounding situation sensor 110.

The vehicle position information 220 indicates the position and theorientation of the vehicle 1. The control device 170 acquires thevehicle position information 220 from the vehicle position sensor 120.Furthermore, the control device 170 may execute a well-known localizingprocessing by the use of the target information included in thesurrounding situation information 210 to increase accuracy of thevehicle position information 220.

The vehicle state information 230 indicates the state of the vehicle 1.The state of the vehicle 1 includes the speed of the vehicle 1 (i.e. thevehicle speed), the acceleration, the steering angle, the yaw rate, andso forth. The state of the vehicle 1 further includes the drivingoperation by the driver of the vehicle 1. The driving operation includesthe acceleration operation, the braking operation, and the steeringoperation. The control device 170 acquires the vehicle state information230 from the vehicle state sensor 130.

The delivery information 240 is information acquired through thecommunication device 140. The control device 170 acquires the deliveryinformation 240 by using the communication device 140 to communicatewith the outside of the vehicle 1. For example, the delivery information240 includes road traffic information (e.g. road work zone information,accident information, traffic restriction information, traffic jaminformation) delivered from an infrastructure. The delivery information240 may include information on the surrounding vehicle acquired throughthe V2V communication.

Furthermore, the control device 170 executes the driving support controlbased on the map information MAP and the driving environment information200. The driving support control is exemplified by the automated drivingcontrol, the trajectory-following control, the lane keep assist control,the collision avoidance control, and so forth. For the purpose of thedriving support control, the control device 170 executes vehicle travelcontrol as appropriate. The vehicle travel control includes steeringcontrol, acceleration control, and deceleration control. The controldevice 170 executes the steering control, the acceleration control, andthe deceleration control by appropriately actuating the travel device160 (i.e. the steering device, the driving device, and the brakingdevice). It can be said that the control device 170 and the traveldevice 160 constitute a “vehicle travel control device” that executesthe vehicle travel control.

As an example of the driving support control, let us consider a casewhere the control device 170 executes the automated driving control. Thecontrol device 170 generates a travel plan for the vehicle 1 based onthe map information MAP and the driving environment information 200. Thetravel plan includes a target route to a destination and a local targettrajectory (e.g. a target trajectory within a lane, a target trajectoryfor a lane change). Moreover, the travel plan includes a vehicle travelcontrol plan for traveling so as to follow the target trajectory,following a traffic rule, avoiding an obstacle, and so forth. Thecontrol device 170 executes the vehicle travel control such that thevehicle 1 travels in accordance with the travel plan.

2-2. Configuration Example of Information Acquisition Device 20

The information acquisition device 20 acquires the driving environmentinformation 200. As shown in FIG. 5, the surrounding situation sensor110, the vehicle position sensor 120, the vehicle state sensor 130, thecommunication device 140, and the control device 170 constitute theinformation acquisition device 20.

2-3. Configuration Example of Database Management Device 30 2-3-1. FirstConfiguration Example

FIG. 7 is a block diagram showing a first configuration example of thedatabase management device 30. In the first configuration example, themap database MAP_DB is installed on the vehicle 1 (the driving supportcontrol device 100). More specifically, the map database MAP_DB isstored in a memory device 180. The memory device 180 may be the same asthe memory device 172 of the control device 170. The control device 170(i.e. the processor 171) manages the map database MAP_DB based on thedriving environment information 200. That is to say, the control device170 serves as the database management device 30.

2-3-2. Second Configuration Example

FIG. 8 is a block diagram showing a second configuration example of thedatabase management device 30. In the second configuration example, thedatabase management device 30 is realized by an external device 300outside the vehicle 1. For example, the external device 300 is amanagement server.

More specifically, the external device 300 includes a memory device 310,a processor 320, and a communication device 330. The map database MAP_DBis stored in the memory device 310. The communication device 330communicates with the communication device 140 of the vehicle 1. Theprocessor 320 performs a variety of information processing by executinga computer program stored in the memory device 310.

The information acquisition device 20 (i.e. the control device 170) ofthe vehicle 1 transmits the driving environment information 200 to theexternal device 300 through the communication device 140. The processor320 of the external device 300 receives the driving environmentinformation 200 from the information acquisition device 20 through thecommunication device 330. Then, the processor 320 manages the mapdatabase MAP_DB based on the driving environment information 200.

Moreover, the driving support control device 100 (i.e. the controldevice 170) of the vehicle 1 sends a request for provision of necessarymap information MAP to the external device 300 through the communicationdevice 140. The processor 320 of the external device 300 reads thenecessary map information MAP from the map database MAP_DB. Then, theprocessor 320 provides the map information MAP to the driving supportcontrol device 100 through the communication device 330.

2-3-3. Third Configuration Example

FIG. 9 is a block diagram showing a third configuration example of thedatabase management device 30. In the third configuration example, themap database MAP_DB is stored in the external device 300, as in the caseof the second configuration example. Meanwhile, the database managementdevice 30 is realized by the control device 170 of the vehicle 1. Thatis, the control device 170 (i.e. the processor 171) remotely manipulatesthe map database MAP_DB on the side of the external device 300.

More specifically, the control device 170 acquires the drivingenvironment information 200 from the information acquisition device 20.Based on the driving environment information 200, the control device 170executes processing such as detecting the road marking candidate,recognizing the vehicle behavior, and determining the evaluation value.When performing registration or update of the road marking mapinformation RM_MAP, the control device 170 transmits a request signalREQ requesting for registration or update to the external device 300through the communication device 140. The request signal REQ includesinformation necessary for the registration or the update. The processor320 of the external device 300 receives the request signal REQ throughthe communication device 330. Then, the processor 320 performs theregistration or the update of the road marking map information RM_MAP inaccordance with the request signal REQ.

2-3-4. Fourth Configuration Example

The functions of the database management device 30 may be distributed tothe control device 170 (i.e. the processor 171) of the vehicle 1 and theprocessor 320 of the external device 300. That is, the above-describedfunctional blocks such as the road marking candidate detection unit, thevehicle behavior recognition unit, the evaluation value determinationunit, and the map information update unit may be distributed to thecontrol device 170 (i.e. the processor 171) and the processor 320.

It is possible to summarize the first to fourth configuration examplesas follows. That is, one processor (i.e. the processor 171 or theprocessor 320) or multiple processors (i.e. the processor 171 and theprocessor 320) serve as the database management device 30.

3. Processing by Database Management Device 30

FIG. 10 is a flow chart showing processing by the database managementdevice 30 according to the present embodiment. The process flow shown inFIG. 10 is repeatedly executed every certain cycle.

3-1. Step S100

The database management device 30 acquires the driving environmentinformation 200 from the information acquisition device 20. Then, thedatabase management device 30 detects the road marking candidate basedon the surrounding situation information 210.

For example, the surrounding situation information 210 includes theimage information obtained by the camera. The database management device30 converts the image information to that in the absolute coordinatesystem based on the position and the orientation of the vehicle 1indicated by the vehicle position information 220. Then, the databasemanagement device 30 uses the image information in the absolutecoordinate system to generate road surface image representing the roadsurface. Alternatively, the road surface image may be generated fromroad surface point cloud measured by the LIDAR, instead of the imageinformation. In this manner, road surface image information is obtainedfrom the surrounding situation information 210. The database managementdevice 30 may register the road surface image information in the mapdatabase MAP_DB.

It should be noted that the process of generating the road surface imageinformation from the surrounding situation information 210 may beexecuted by the information acquisition device 20. In that case, thedatabase management device 30 acquires the surrounding situationinformation 210 including the road surface image information from theinformation acquisition device 20.

Subsequently, the database management device 30 extracts the roadmarking candidate from the road surface image indicated by the roadsurface image information. For example, the database management device30 executes binarization processing or edge detection processing toextract a white line that seems to be the stop line from the roadsurface image. A prescribed width of the stop line in Japan is from 0.3m to 0.45 m. A white line that deviates from the prescribed width alittle may also be extracted in consideration of variability andblurring of the white line. The same applies to the pedestrian crossing.The database management device 30 extracts a stripe area that seems tobe the pedestrian crossing from the road surface image, in considerationof a prescribed width and variability of the white line. Alternatively,the database management device 30 may extract the road marking candidatefrom the road surface image by utilizing an extraction tool generatedthrough machine learning.

It should be noted that the road marking candidate may include not onlythe specific road marking RM such as the stop line and the pedestriancrossing but also the lane marking LM such as the lane boundary line andthe center line.

3-2. Step S200

The vehicle 1 passes the road marking candidate detected in Step S100.The database management device 30 recognizes vehicle behavior of thevehicle 1 in a period when passing the road marking candidate. Forexample, the database management device 30 recognizes the vehiclebehavior of the vehicle 1 in the certain section RNG including theposition of the road marking candidate (see FIG. 4). The vehiclebehavior of the vehicle 1 can be recognized based on at least one of thevehicle position information 220 and the vehicle state information 230.

As another example, another vehicle 2 (see FIG. 4) passes the roadmarking candidate detected in Step S100. The database management device30 recognizes vehicle behavior of said another vehicle 2 in a periodwhen passing the road marking candidate. For example, the databasemanagement device 30 recognizes the vehicle behavior of another vehicle2 in the certain section RNG including the position of the road markingcandidate. The vehicle behavior of another vehicle 2 can be recognizedbased on the surrounding situation information 210. As another example,the vehicle behavior of another vehicle 2 may be recognized based on thedelivery information 240 (specifically, V2V communication information).

In this manner, the database management device 30 recognizes the vehiclebehavior of at least one of the vehicle 1 and another vehicle 2 in aperiod when passing the road marking candidate, based on the drivingenvironment information 200.

3-3. Step S300

The database management device 30 determines, based on the vehiclebehavior recognized in Step S200, the evaluation value that indicatescertainty of the road marking candidate being the specific road markingRM. There are various examples of Steps S200 and S300. Various examplesof Steps S200 and S300 will be described in the subsequent Section 4 indetail.

3-4. Step S400

The database management device 30 compares the evaluation valuedetermined in Step S300 with a threshold. When the evaluation value isequal to or higher than the threshold (Step S400; Yes), the processingproceeds to Step S500. On the other hand, when the evaluation value isless than the threshold (Step S400; No), the processing proceeds to StepS600.

3-5. Step S500

The database management device 30 registers the road marking candidateas the specific road marking RM in the road marking map informationRM_MAP. More specifically, the database management device 30 registersthe position of the specific road marking RM in the road marking mapinformation RM_MAP. The database management device 30 may register theposition of the specific road marking RM and the evaluation valueassociated with each other, in the road marking map information RM_MAP(see FIGS. 2 and 3).

3-6. Step S600

The database management device 30 discards the road marking candidatehaving a low evaluation value.

4. Determination of Evaluation Value Based on Vehicle Behavior (StepsS200, S300)

Next, various examples of Steps S200 and S300 will be described.

4-1. First Example

FIGS. 11 and 12 are conceptual diagrams for explaining a first example.In the first example, we consider the “stop line candidate” being acandidate for the stop line SL. The stop line evaluation value Pslindicates certainty of the stop line candidate being the stop line SL.It should be noted that the stop line SL here includes the mandatorystop line.

FIG. 11 shows a situation where the vehicle 1 passes the stop line SL.In general, a trajectory TR of the vehicle 1 passing the stop line SL isalmost orthogonal to a longitudinal direction L of the stop line SL. Inother words, an angle θ between the trajectory TR of the vehicle 1 andthe longitudinal direction L of the stop line SL is close to 90 degrees.On the other hand, FIG. 12 shows another situation where the vehicle 1crosses a center line CL. An angle θ between the trajectory TR of thevehicle 1 and a longitudinal direction L of the center line CL is small.Therefore, it is possible to determine the stop line evaluation valuePsl based on the angle θ.

More specifically, the database management device 30 recognizes thetrajectory TR of the vehicle 1 passing the stop line candidate as thevehicle behavior, based on the vehicle position information 220. Then,the database management device 30 calculates an angle θ between thetrajectory TR of the vehicle 1 and the longitudinal direction L of thestop line candidate. The database management device 30 increases thestop line evaluation value Psl as the angle θ is closer to 90 degrees.In other words, the database management device 30 calculates the stopline evaluation value Psl to be higher as the angle θ is closer to 90degrees.

4-2. Second Example

A second example is a modification example of the first example. In thesecond example, a trajectory TR of another vehicle 2 (see FIG. 4)instead of the vehicle 1 is used. More specifically, the databasemanagement device 30 recognizes the trajectory TR of another vehicle 2passing the stop line candidate as the vehicle behavior, based on thesurrounding situation information 210. Then, the database managementdevice 30 calculates an angle θ between the trajectory TR of saidanother vehicle 2 and the longitudinal direction L of the stop linecandidate. The database management device 30 increases the stop lineevaluation value Psl as the angle θ is closer to 90 degrees. In otherwords, the database management device 30 calculates the stop lineevaluation value Psl to be higher as the angle θ is closer to 90degrees.

4-3. Third Example

FIGS. 13 and 14 are conceptual diagrams for explaining a third example.In the third example, we consider the mandatory stop line MSL. Themandatory stop line evaluation value Pmsl indicates certainty of thestop line candidate being the mandatory stop line MSL. When the vehicle1 passes the stop line candidate, the database management device 30determines the mandatory stop line evaluation value Pmsl in addition tothe stop line evaluation value Psl described in the above first andsecond examples.

FIG. 13 shows a speed when the vehicle 1 passes the mandatory stop lineMSL. The vehicle 1 is required to always stop before the mandatory stopline MSL. Therefore, the speed of the vehicle 1 on the mandatory stopline MSL is generally low. On the other hand, FIG. 14 shows a speed whenthe vehicle 1 passes the stop line SL other than the mandatory stop lineMSL. The vehicle 1 does not necessarily stop before the stop line SL. Itis therefore possible to determine the mandatory stop line evaluationvalue Pmsl based on the speed of the vehicle 1 on the stop linecandidate. It should be noted that “on the stop line candidate” heremeans a position of the stop line candidate and its vicinity.

More specifically, the database management device 30 recognizes thespeed of the vehicle 1 on the stop line candidate (hereinafter referredto as a “passing speed Vp”) as the vehicle behavior, based on thevehicle state information 230. Then, the database management device 30increases the mandatory stop line evaluation value Pmsl as the passingspeed Vp is lower. In other words, the database management device 30calculates the mandatory stop line evaluation value Pmsl to be higher asthe passing speed Vp is lower.

Alternatively, the database management device 30 may compare the passingspeed Vp with a speed threshold Vth. An “increase condition” is that thepassing speed Vp is lower than the speed threshold Vth. When theincrease condition is satisfied, the database management device 30increases the mandatory stop line evaluation value Pmsl from a referencevalue. On the other hand, a “decrease condition” is that the passingspeed Vp is equal to or higher than the speed threshold Vth. When thedecrease condition is satisfied, the database management device 30decreases the mandatory stop line evaluation value Pmsl from thereference value.

4-4. Fourth Example

There may be a case where the passing speed Vp on the stop line SL otherthan the mandatory stop line MSL happens to be low due to traffic jamand the like. In that case, the mandatory stop line evaluation valuePmsl may become high despite the stop line SL. In view of the above, afourth example proposes a method for further increasing accuracy of themandatory stop line evaluation value Pmsl. The fourth example isimplemented in combination with the third example.

FIG. 15 is a conceptual diagram for explaining the fourth example. Letus consider a situation when the vehicle 1 stops before the stop linecandidate. When a preceding vehicle 3 exists ahead of the vehicle 1,there is a high possibility that the vehicle 1 stops due to the presenceof the preceding vehicle 3. On the other hand, when no preceding vehicle3 exists ahead of the vehicle 1, there is a high possibility that thestop line candidate is the mandatory stop line MSL. It is thereforepossible to adjust the mandatory stop line evaluation value Pmslobtained in the third example according to presence or absence of thepreceding vehicle 3.

More specifically, the database management device 30 determines, basedon the surrounding situation information 210, whether or not anypreceding vehicle 3 exists in a certain area ahead of the vehicle 1. An“increase condition” is that the vehicle 1 stops in the certain areabefore the stop line candidate despite absence of the preceding vehicle3. The certain area is an area before the stop line candidate in which avehicle is generally considered to stop. When the increase condition issatisfied, the database management device 30 adds a correction value tothe mandatory stop line evaluation value Pmsl obtained in the thirdexample. That is, the database management device 30 increases themandatory stop line evaluation value Pmsl.

4-5. Fifth Example

A fifth example also proposes a method for further increasing accuracyof the mandatory stop line evaluation value Pmsl, as in the case of thefourth example. The fifth example is implemented in combination with thethird example or the fourth example.

FIGS. 16 and 17 are conceptual diagrams for explaining the fifthexample. FIG. 16 shows a speed and an acceleration when the vehicle 1passes the mandatory stop line MSL. The vehicle 1 is required to alwaysstop before the mandatory stop line MSL. Therefore, switching fromdeceleration to acceleration of the vehicle 1 occurs before themandatory stop line MSL. On the other hand, FIG. 17 shows a speed and anacceleration when the vehicle 1 passes the stop line SL other than themandatory stop line MSL. The switching from deceleration to accelerationdoes not necessarily occur before the stop line SL. It is thereforepossible to adjust the mandatory stop line evaluation value Pmslobtained in the third example according to presence or absence of theswitching.

More specifically, the database management device 30 determines, basedon the vehicle state information 230 (i.e. the acceleration), whether ornot the switching from deceleration to acceleration of the vehicle 1occurs in a certain area before the stop line candidate. An “increasecondition” is that the switching occurs. When the increase condition issatisfied, the database management device 30 adds a correction value tothe mandatory stop line evaluation value Pmsl obtained in the thirdexample. That is, the database management device 30 increases themandatory stop line evaluation value Pmsl. On the other hand, a“decrease condition” is that the switching does not occur. When thedecrease condition is satisfied, the database management device 30subtracts a correction value from the mandatory stop line evaluationvalue Pmsl obtained in the third example. That is, the databasemanagement device 30 decreases the mandatory stop line evaluation valuePmsl.

4-6. Sixth Example

A sixth example also proposes a method for further increasing accuracyof the mandatory stop line evaluation value Pmsl, as in the case of thefourth example. The sixth example is implemented in combination with anyof the third to fifth examples.

FIGS. 18 and 19 are conceptual diagrams for explaining the sixthexample. FIG. 18 shows as speed and a driving operation when the vehicle1 passes the mandatory stop line MSL. The vehicle 1 is required toalways stop before the mandatory stop line MSL. Therefore, operationswitching from a braking operation to an acceleration operation by thedriver occurs before the mandatory stop line MSL. On the other hand,FIG. 19 shows a speed and a driving operation when the vehicle 1 passesthe stop line SL other than the mandatory stop line MSL. The operationswitching from the braking operation to the acceleration operation doesnot necessarily occur before the stop line SL. It is therefore possibleto adjust the mandatory stop line evaluation value Pmsl obtained in thethird example according to presence or absence of the operationswitching.

More specifically, the database management device 30 determines, basedon the vehicle state information 230 (i.e. the driving operation),whether or not the operation switching from the braking operation to theacceleration operation by the driver occurs in a certain area before thestop line candidate. An “increase condition” is that the operationswitching occurs. When the increase condition is satisfied, the databasemanagement device 30 adds a correction value to the mandatory stop lineevaluation value Pmsl obtained in the third example. That is, thedatabase management device 30 increases the mandatory stop lineevaluation value Pmsl. On the other hand, a “decrease condition” is thatthe operation switching does not occur. When the decrease condition issatisfied, the database management device 30 subtracts a correctionvalue from the mandatory stop line evaluation value Pmsl obtained in thethird example. That is, the database management device 30 decreases themandatory stop line evaluation value Pmsl.

It should be noted that in the third to sixth examples described above,vehicle state information regarding another vehicle 2 may be usedinstead of the vehicle state information 230 regarding the vehicle 1.For example, when the database management device 30 is installed on thevehicle 1 (see FIG. 7), the database management device 30 can acquirethe vehicle state information from another vehicle 2 through the V2Vcommunication.

4-7. Seventh Example

FIGS. 20 and 21 are conceptual diagrams for explaining a seventhexample. In the seventh example, we consider the “pedestrian crossingcandidate” being a candidate for the pedestrian crossing PC. Thepedestrian crossing evaluation value Ppc indicates certainty of thepedestrian crossing candidate being the pedestrian crossing PC.

FIG. 20 shows a situation where the vehicle 1 passes the pedestriancrossing PC. In general, a trajectory TR of the vehicle 1 passing thepedestrian crossing PC is almost orthogonal to the arrangement directionA of the pedestrian crossing PC. In other words, an angle θ between thetrajectory TR of the vehicle 1 and the arrangement direction A of thepedestrian crossing PC is close to 90 degrees. On the other hand, FIG.21 shows another situation where the vehicle 1 passes a no-parkingmarking NP. An angle θ between the trajectory TR of the vehicle 1 and anarrangement direction A of the no-parking marking NP is small.Therefore, it is possible to determine the pedestrian crossingevaluation value Ppc based on the angle θ.

More specifically, the database management device 30 recognizes thetrajectory TR of the vehicle 1 passing the pedestrian crossing candidateas the vehicle behavior, based on the vehicle position information 220.Then, the database management device 30 calculates an angle θ betweenthe trajectory TR of the vehicle 1 and the arrangement direction A ofthe pedestrian crossing candidate. The database management device 30increases the pedestrian crossing evaluation value Ppc as the angle θ iscloser to 90 degrees. In other words, the database management device 30calculates the pedestrian crossing evaluation value Ppc to be higher asthe angle θ is closer to 90 degrees.

4-8. Eighth Example

An eighth example is a modification example of the seventh example. Inthe eighth example, a trajectory TR of another vehicle 2 (see FIG. 4)instead of the vehicle 1 is used. More specifically, the databasemanagement device 30 recognizes the trajectory TR of another vehicle 2passing the pedestrian crossing candidate as the vehicle behavior, basedon the surrounding situation information 210. Then, the databasemanagement device 30 calculates an angle θ between the trajectory TR ofsaid another vehicle 2 and the arrangement direction A of the pedestriancrossing candidate. The database management device 30 increases thepedestrian crossing evaluation value Ppc as the angle θ is closer to 90degrees. In other words, the database management device 30 calculatesthe pedestrian crossing evaluation value Ppc to be higher as the angle θis closer to 90 degrees.

4-9. Ninth Example

In a ninth example, a result of recognition of the white line in StepS100 is taken into consideration. For example, when the white linedetected as the road marking candidate is blurred, the databasemanagement device 30 calculates the evaluation value to be low. Asanother example, when a difference in brightness between the white linedetected as the road marking candidate and its surrounding area issmall, the database management device 30 calculates the evaluation valueto be low.

4-10. Tenth Example

It is also possible to combine some of the first to ninth examplesdescribed above, as long as there is no contradiction.

5. Update of Evaluation Value of Road Marking Map Information

Next, update of the evaluation value of the road marking map informationRM_MAP will be described. Here, we consider a case where the roadmarking map information RM_MAP indicates the evaluation value inaddition to the position of the specific road marking RM. The specificroad marking RM that is already registered in the road marking mapinformation RM_MAP is hereinafter referred to as a “registered roadmarking”.

When the vehicle 1 repeatedly travels a same road, an identical roadmarking RM is repeatedly detected and information on the identical roadmarking RM is repeatedly acquired. In other words, the databasemanagement device 30 newly acquires information on the registered roadmarking. Whether or not the road marking candidate is the same as theregistered road marking is determined based on the position. Forexample, an equivalent area that can be regarded as the same position asthe registered road marking is set in consideration of a detection errorof the surrounding situation sensor 110. It is determined that the roadmarking candidate included in the equivalent area is the same as theregistered road marking.

When newly acquiring information on the road marking candidatecorresponding to the registered road marking (i.e. the road markingcandidate being the same as the registered road marking), the databasemanagement device 30 updates the information on the registered roadmarking. For example, the database management device 30 updates theevaluation value regarding the registered road marking, based on thevehicle behavior with respect to the road marking candidatecorresponding to the registered road marking. For example, an averagevalue or a weighted average of the evaluation values calculated so faris registered in the road marking map information RM_MAP. In the case ofthe weighted average value, it is preferable that a weight for thelatest evaluation value is set to be the largest.

As to the stop line candidate, the mandatory stop line evaluation valuePmsl is determined in addition to the stop line evaluation value Psl, asdescribed in the above Section 4. The mandatory stop line evaluationvalue Pmsl may be updated to increase or decrease according to theabove-described “increase condition” or “decrease condition”. Forexample, an initial value of the mandatory stop line evaluation valuePmsl is set. The database management device 30 determines whether theincrease condition or the decrease condition is satisfied. When theincrease condition is satisfied, the database management device 30increases the mandatory stop line evaluation value Pmsl regarding theregistered road marking. On the other hand, when the decrease conditionis satisfied, the database management device 30 decreases the mandatorystop line evaluation value Pmsl regarding the registered road marking.

FIG. 22 shows an example of the update of the mandatory stop lineevaluation value Pmsl. In the example shown in FIG. 22, the stop linecandidate is the stop line SL other than the mandatory stop line MSL. Nrepresents the number of times of passing the stop line candidate. Atthe first passing (N=1), the vehicle 1 does not stop before the stopline candidate. At the second passing (N=2), the vehicle 1 stops beforethe stop line candidate in order to give way to a pedestrian. As aresult, the mandatory stop line evaluation value Pmsl is increased.However, at the third passing (N=3), the vehicle 1 does not stop beforethe stop line candidate. As a result, the mandatory stop line evaluationvalue Pmsl is decreased. As seen above, accuracy of the mandatory stopline evaluation value Pmsl is maintained due to the update of themandatory stop line evaluation value Pmsl.

FIG. 23 shows another example of the update of the mandatory stop lineevaluation value Pmsl. In the example shown in FIG. 23, the stop linecandidate is the mandatory stop line MSL. The vehicle 1 stops before thestop line candidate every time. As a result, the mandatory stop lineevaluation value Pmsl keeps increasing. As seen above, accuracy of themandatory stop line evaluation value Pmsl is increased due to the updateof the mandatory stop line evaluation value Pmsl.

FIG. 24 is a flow chart showing an example of the processing by thedatabase management device 30. An overlapping description with theforegoing FIG. 10 will be omitted as appropriate. In the example shownin FIG. 24, Step S110 is added between Step S100 and Step S200.

In Step S110, the database management device 30 reads out the roadmarking map information RM_MAP and merges the registered road markingwith the road marking candidate. That is, the database management device30 combines the road marking candidate detected in Step S100 and theregistered road marking. When the road marking candidate detected inStep S100 is the same as the registered road marking, they are mergedinto a single road marking candidate. When no road marking candidateidentical to the registered road marking is detected in Step S100, theregistered road marking may be discarded.

After that, the database management device 30 executes Steps S200 toS600. In Step S500, the database management device 30 updates the roadmarking map information RM_MAP.

The update processing described above causes further increase in theaccuracy (quality) of the road marking map information RM_MAP. As aresult, the accuracy of the driving support control using the roadmarking map information RM_MAP also is further increased.

6. Other Processing

In Step S100 described above, the database management device 30 detectsthe road marking candidate. Here, the following problem is considered.For example, when a stop line is blurred, the stop line may not becorrectly detected as the stop line candidate. As another example, whena character road marking “STOP” is present in the vicinity of the stopline (mandatory stop line), not only the stop line but also a transverseline included in “STOP” may be detected as the stop line candidate. Inthis case, a plurality of stop line information may be registered in theroad marking map information RM_MAP, although only a single stop lineexists in reality. Hereinafter, a method for dealing with such excess ordeficiency of the stop line candidate will be described.

In the present example, the database management device 30 acquiresnavigation map information. The navigation map information indicatespresence or absence of intersections, stop lines, and pedestriancrossings, and their rough positions. That is to say, the navigation mapinformation indicates the position of the specific road marking RM withlower accuracy than the road marking map information RM_MAP. Such thenavigation map information is included in the map database MAP_DB. Thedatabase management device 30 acquires the navigation map informationfrom the map database MAP_DB.

FIG. 25 is a flow chart showing an example of processing by the databasemanagement device 30. An overlapping description with the foregoing FIG.10 will be omitted as appropriate.

After Step S100, the database management device 30 compares a result ofdetection of the road marking candidate in Step S100 with the navigationmap information (Step S120). When the specific road marking RM indicatedby the navigation map information is not detected as the road markingcandidate, it means that the road marking candidate is deficient. Whenthe road marking candidate is deficient (Step S120; Yes), the processingproceeds to Step S130. Otherwise (Step S120; No), the processingproceeds to Step S200.

In Step S130, the database management device 30 increases sensitivity ofthe detection processing for detecting the road marking candidate. Forexample, the database management device 30 lowers an extractionthreshold used for extracting the white line from the road surfaceimage. After that, the processing returns back to Step S100. Thedatabase management device 30 executes the detection processing againwith respect to an area where the road marking candidate is deficient.

Moreover, after Step S400, the database management device 30 comparesthe result of detection of the road marking candidate in Step S100 withthe navigation map information (Step S410). When a plurality of roadmarking candidates are detected in the vicinity of the specific roadmarking RM indicated by the navigation map information, it means thatthe road marking candidate is excessive. When the road marking candidateis excessive (Step S410; Yes), the processing proceeds to Step S420.Otherwise (Step S410; No), the processing proceeds to Step S500.

In Step S420, the database management device 30 compares respectiveevaluation values of the plurality of road marking candidates. Then, thedatabase management device 30 discards the road marking candidate havinglower evaluation value and selects the road marking candidate having thehighest evaluation value. After that, the processing proceeds to StepS500. The database management device 30 registers the road markingcandidate having the highest evaluation value, as the specific roadmarking RM, in the road marking map information RM_MAP.

The processing of Steps S410 and S420 may be executed after the mergeprocessing (Step S110) described in the above FIG. 24 is executed. Inthat case, it is expected that the road marking candidate erroneouslyregistered in the road marking map information RM_MAP is discarded.

What is claimed is:
 1. A map information system comprising: one or moreprocessors configured to manage a map database used for driving supportcontrol that supports driving of a vehicle, wherein the map databaseincludes road marking map information that indicates a position of aspecific road marking including at least one of a stop line and apedestrian crossing, driving environment information indicates drivingenvironment for the vehicle that is acquired by a sensor installed onthe vehicle, the one or more processors are further configured to:detect a road marking candidate being a candidate for the specific roadmarking around the vehicle, based on the driving environmentinformation; recognize vehicle behavior of at least one of the vehicleand another vehicle in a period when passing the road marking candidate,based on the driving environment information; determine, based on thevehicle behavior, an evaluation value that indicates certainty of theroad marking candidate being the specific road marking; and register theroad marking candidate having the evaluation value equal to or higherthan a threshold, as the specific road marking, in the road marking mapinformation, the specific road marking includes the stop line, the roadmarking candidate includes a stop line candidate which is a candidatefor the stop line, a stop line evaluation value is an evaluation valuethat indicates certainty of the stop line candidate being the stop line,and the one or more processors are further configured to: recognize atrajectory of the vehicle or the other vehicle passing the stop linecandidate as the vehicle behavior, based on the driving environmentinformation; and increase the stop line evaluation value as an anglebetween a longitudinal direction of the stop line candidate and thetrajectory of the vehicle or the other vehicle is closer to 90 degrees.2. The map information system according to claim 1, wherein the stopline includes a mandatory stop line, a mandatory stop line evaluationvalue is an evaluation value that indicates certainty of the stop linecandidate being the mandatory stop line, the driving environmentinformation includes vehicle state information indicating a speed of thevehicle, and the one or more processors are further configured to:recognize the speed on the stop line candidate as the vehicle behavior,based on the vehicle state information; and increase the mandatory stopline evaluation value as the speed on the stop line candidate is lower.3. The map information system according to claim 1, wherein the stopline includes a mandatory stop line, a mandatory stop line evaluationvalue is an evaluation value that indicates certainty of the stop linecandidate being the mandatory stop line, the driving environmentinformation includes vehicle state information indicating a speed of thevehicle, and the one or more processors are further configured to:recognize the speed on the stop line candidate as the vehicle behavior,based on the vehicle state information; increase the mandatory stop lineevaluation value, when the speed on the stop line candidate is lowerthan a speed threshold; and decrease the mandatory stop line evaluationvalue, when the speed on the stop line candidate is equal to or higherthan the speed threshold.
 4. The map information system according toclaim 2, wherein the driving environment information includessurrounding situation information indicating a situation around thevehicle, and the one or more processors are further configured to:determine, based on the surrounding situation information, whether apreceding vehicle exists ahead of the vehicle; and increase themandatory stop line evaluation value, when the vehicle stops in acertain area before the stop line candidate despite absence of thepreceding vehicle.
 5. The map information system according to claim 2,wherein the one or more processors are further configured to: determine,based on the vehicle state information, whether switching fromdeceleration to acceleration of the vehicle occurs in a certain areabefore the stop line candidate; increase the mandatory stop lineevaluation value, when the switching occurs in the certain area beforethe stop line candidate; and decrease the mandatory stop line evaluationvalue, when the switching does not occur in the certain area before thestop line candidate.
 6. The map information system according to claim 2,wherein the vehicle state information further indicates a drivingoperation by a driver of the vehicle, and the one or more processors arefurther configured to: determine, based on the vehicle stateinformation, whether operation switching from a braking operation to anacceleration operation by the driver occurs in a certain area before thestop line candidate; increase the mandatory stop line evaluation value,when the operation switching occurs in the certain area before the stopline candidate; and decrease the mandatory stop line evaluation value,when the operation switching does not occur in the certain area beforethe stop line candidate.
 7. A map information system comprising: one ormore processors configured to manage a map database used for drivingsupport control that supports driving of a vehicle, wherein the mapdatabase includes road marking map information that indicates a positionof a specific road marking including at least one of a stop line and apedestrian crossing, driving environment information indicates drivingenvironment for the vehicle that is acquired by a sensor installed onthe vehicle, the one or more processors are further configured to:detect a road marking candidate being a candidate for the specific roadmarking around the vehicle, based on the driving environmentinformation; recognize vehicle behavior of at least one of the vehicleand another vehicle in a period when passing the road marking candidate,based on the driving environment information; determine, based on thevehicle behavior, an evaluation value that indicates certainty of theroad marking candidate being the specific road marking; and register theroad marking candidate having the evaluation value equal to or higherthan a threshold, as the specific road marking, in the road marking mapinformation, the specific road marking includes the pedestrian crossing,the pedestrian crossing has a stripe pattern that a plurality of linesorthogonal to a first direction are arranged in parallel, the roadmarking candidate includes a pedestrian crossing candidate which is acandidate for the pedestrian crossing, a pedestrian crossing evaluationvalue is an evaluation value that indicates certainty of the pedestriancrossing candidate being the pedestrian crossing, and the one or moreprocessors are further configured to: recognize a trajectory of thevehicle or the other vehicle passing the pedestrian crossing candidateas the vehicle behavior, based on the driving environment information;and increase the pedestrian crossing evaluation value as an anglebetween the first direction of the pedestrian crossing candidate and thetrajectory of the vehicle is closer to 90 degrees.